/**
 * Copyright (c) 2011-2012, Lukas Eder, lukas.eder@gmail.com
 * All rights reserved.
 *
 * This software is licensed to you under the Apache License, Version 2.0
 * (the "License"); You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * . Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * . Neither the name "jOOX" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package org.joox;

import java.util.Iterator;

import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * @author Lukas Eder
 */
class Elements implements Iterable<Element> {

    private final NodeList elements;
    private final int      length;

    Elements(NodeList elements) {
        this.elements = elements;
        this.length = elements.getLength();
    }

    @Override
    public Iterator<Element> iterator() {
        return new ElementIterator();
    }

    private class ElementIterator implements Iterator<Element> {

        private int     i    = 0;
        private Element next = null;

        @Override
        public boolean hasNext() {
            return (next != null) || ((next = findNext()) != null);
        }

        @Override
        public Element next() {
            try {
                return findNext();
            }
            finally {
                next = null;
            }
        }

        /**
         * Find next element, skipping all non-element nodes
         */
        private Element findNext() {
            if (next == null) {
                while (i < length) {
                    Node node = elements.item(i++);

                    if (node.getNodeType() == Node.ELEMENT_NODE) {
                        next = (Element) node;
                        break;
                    }
                }
            }

            return next;
        }

        @Override
        public void remove() {
            throw new UnsupportedOperationException();
        }
    }
}
